A free-to-play version, entitled Unreal Tournament 3 X, was leaked in late 2022 and cancelled in the following year.

The game's single-player campaign does not follow a plot based around the eponymous tournament, but rather a Necris attack that occurs on a colony on an unknown planet, releasing armed Kralls, a warlike race of aliens, on the humans.

The following game modes are included: Modes not returning from the prior Unreal Tournament games include Invasion, Mutant (having been later on partially replaced by the Titan mutator in the UT3 Titan Pack), Onslaught (replaced by Warfare), Bombing Run, Last Man Standing, Domination, and Double Domination.

The five playable factions are: the Iron Guard, a team of human mercenaries affiliated with the Axon; the Ronin, a band of four survivors of a Skaarj attack on a human colony; Liandri studius, a series of advanced humanoid robots custom-built or retrofitted for combat; the Krall, a warlike race of aliens formerly under the leadership of the Skaarj, returning from their initial appearance in the original Unreal; and the Necris, warriors who have undergone the process of the same name, making them stronger at the expense of replacing their biological processes with "Nanoblack", effectively turning them into undead soldiers (hence the name, Necris).

In the game's story, a Necris attack occurs on the Twin Souls colony of Taryd, an Earth-like planet, releasing bloodthirsty reptilian Krall on the humans.

Reaper is rescued by Othello and Jester and wakes up in the base of the Izanagi, a megacorporation with a large private army, and meets with their leader Malcolm, a celebrated former tournament champion.

Malcolm promises Reaper and the rest of Ronin that if they join the Izanagi, they will take the fight to the Necris and avenge the massacre of Twin Souls.

The missions of the campaign are identical to multiplayer matches, with the only difference being the enemies are computer-controlled bots instead of human players.

The Necris are seen deploying tentacle-like tubes carrying Nanoblack into the planet's surface from orbit, in order to terraform the entire world.

However, it is revealed that Malcolm has betrayed Ronin, allowing Necris troops to surround and kill Jester, Bishop, and Othello.

The Limited Collector's Edition was sold in the United States, Canada, Latin America, Europe, South Africa, Australia and most other territories.

[9] The PlayStation 3 version supports community-made mods that can be uploaded and downloaded to the PS3's HDD or external media, as well as mouse and keyboard inputs.

The Linux and Mac OS X versions of the game were planned to be released as downloadable installers that work with the retail disc.

A new patch was also released in conjunction with the Titan Pack, which allowed for various AI improvements (especially in vehicle modes), networking performance upgrades and added support for Steam Achievements (PC) and Trophies (PS3).

[44] PlayStation: the Official Magazine gave it 5 stars out of 5 in its February 2008 issue, commending the game for graphics and gameplay.